Storage system and data relocation control device

ABSTRACT

The present invention achieves data relocation in accordance with a user&#39;s policies, in an environment where a plurality of storage devices are combined. The volumes belonging to storage devices A-D are managed virtually integrally. A host recognizes a plurality of storage devices A-D as a single virtual storage device. The user is able to group the volumes belonging to the storage system, as a plurality of storage layers  1 - 3.  For example, storage layer  1  can be defined as a high-reliability layer, storage layer  2,  as a low-cost layer, and storage layer  3,  as an archive layer. Each storage layer is constituted by a group of volumes corresponding to respective policies (high reliability, low cost, archiving). The user designates volumes to be moved V 1  and V 2,  in group units, and indicates a storage layer forming a movement destination, whereby the data is relocated.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application relates to and claims priority from Japanese PatentApplication No. 2004-250327 filed on Aug. 30, 2004, the entiredisclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a storage system and a data relocationcontrol device.

The storage system is constituted by comprising at least one or morestorage device, known as a disk array sub-system, for example. Thisstorage device provides a storage region based on a RAID (RedundantArrays of Independent Disks), wherein disk drives, such as hard diskdrives, semiconductor memory drives, or the like, are arranged in anarray configuration, for example. A host computer (hereinafter, called“host”) accesses the logical storage region provided by the storagedevice and reads or writes data.

The amount of data managed by businesses and organizations such asregional authorities, educational institutions, financial institutions,government and municipal offices, and the like, is growing steadily yearon year, and storage devices are added and replaced as this data volumeincreases. As the data volume increases and the composition of storagesystems becomes more complicated in this way, techniques have beenproposed for improving the efficiency of use of storage systems bylocating the data relating to various application programs, such as mainmanagement software and database management software, in suitablelocations according to the value of that data (Japanese Patent Laid-openNo. 2003-345522, Japanese Patent Laid-open No. 2001-337790, JapanesePatent Laid-open No. 2001-67187, Japanese Patent Laid-open No.2001-249853, and Japanese Patent Laid-open No. 2004-70403.)

The respective reference patents mentioned above disclose techniques forrelocating data by copying data stored in one volume to another volume,on the basis of disk performance information and use information.

However, in the techniques described in these references, it isnecessary to relocate data individually, in volume units, and the useris not able to move volumes between freely defined layers, and henceusability is poor. Moreover, in the techniques described in theaforementioned patent references, since data is relocated in volumeunits, it is difficult to relocate data in a group of related volumes,together, in one operation. Furthermore, the techniques described in theaforementioned patent references focus exclusively on the relocation ofthe data, and do not give consideration to the processing afterrelocation of the data. Therefore, usability is poor from this viewpointalso.

SUMMARY OF THE INVENTION

One object of the present invention is to provide a storage system and adata relocation control device capable of relocating data distributedover a plurality of storage devices, in a more simple fashion.Furthermore, one object of the present invention is to provide a storagesystem and a data relocation control device having improved usability,by allowing the data stored respectively in a plurality of mutuallyrelated volumes to be relocated together, in one operation. Moreover,one object of the present invention is to provide a storage system and adata relocation control device having improved usability, by causing theprocessing required after data relocation to be executed automatically.Other objects of the present invention will become apparent from thefollowing description of the embodiments.

In order to achieve the aforementioned objects, the storage systemaccording to the present invention comprises: a plurality of storagedevices respectively having at least one or more volumes; avirtualization section for managing the volumes belonging to therespective storage devices, virtually, in a unified fashion; a storagesection for storing volume attribute information for managing theattribute information of each of the volumes; and a relocating sectionfor relocating a designated movement source volume to a designatedstorage layer, with respect to a plurality of storage layersrespectively generated on the basis of a plurality of previouslydetermined policies and the volume attribute information.

Here, a “policy” can be set as desired by the user, and the same volumecan belong to different storage layers. Moreover, the storage layers canbe set in units corresponding to each storage device, or they can be setto span a plurality of storage devices.

For example, storage layer management information containing policyidentification information for respectively identifying each of thepolicies, and layer composition conditions respectively associated witheach of the policy identification information, is provided, and storagelayers corresponding to each of the policies can be generatedrespectively by means of a group of volumes satisfying the respectivelayer composition conditions. The layer composition conditions mayinclude at least one of the RAID level, the drive type, the storagecapacity, the type of storage device, and the use status.

More specifically, the storage layers are generated in accordance withpolicies defined by the user, such as a high-performance layerconstituted by high-performance disks, a low-cost layer constituted bylow-cost disks, and the like. One or a plurality of volumes belonging tothe respective storage layers may be located in the same storage device,or they may be located in different storage devices.

The policies defining the respective layers are determined by layercomposition conditions which can be set by the user. For example, whendefining a high-performance layer, the user should establish conditionsfor selecting high-performance disks and high-performance storagedevices, as the layer composition conditions. Moreover, for example,when defining a low-cost layer, the user should set conditions forselecting inexpensive disks, as the layer composition conditions. Thestorage layer is composed by means of volumes which satisfy therespective layer composition conditions.

When data in a volume belonging to a particular storage layer is to berelocated, then the source volume and the target storage layer should bedesignated, respectively. Consequently, the data in the designatedsource volume is moved to a volume belonging to the designated targetstorage layer.

The relocating section is able to relocate the designated sourcevolumes, in units of groups, each group consisting of a plurality ofmutually related volumes, for example. The plurality of mutually relatedvolumes may be, for example, a group of volumes storing data used by thesame application program, or a group of volumes storing data forming thesame file system, or the like. It is still possible to group volumestogether, even if there is little relation between the respective data.

The relocating section can also execute prescribed processing that hasbeen associated previously with the target storage layer, with respectto the moved volume, when the designated source volume has been moved tothe target storage layer. The prescribed processing may be, for example,setting of access attributes, such as a read-only setting, or creationof redundant volumes, or the like.

The relocating section includes a target candidate selecting section forselecting a target candidate volume to which the storage contents of thedesignated source volume can be copied, and a presenting section forpresenting the target candidate volume selected by the target candidateselecting section, to the user; and the target candidate selectingsection can select a volume having matching essential attributes thatare previously established from among the attributes of the sourcevolume, as the target candidate volume, by referring to the volumeattribute information.

The volume attribute information may comprise static attributes anddynamic attributes, and prescribed attributes of the static attributesmay be set as the essential attributes. The essential attributes mayinclude at the least the storage capacity of the volume.

In this way, the relocating section selects volumes which match theessential attributes of the source volume, as target candidate volumes.If there are a plurality of target candidate volumes having matchingessential attributes, then the target candidate selecting sectionselects only one of the target candidate volumes, on the basis of thedegree of matching of other attributes apart from the essentialattributes. Attributes other than the essential attributes may be, forexample, the RAID level, the disk type, the model of storage device, andthe like. In other words, if a plurality of volumes matching theessential attributes are extracted, then the volume of these volumeshaving a composition most closely resembling that of the source volumeis selected as the target candidate volume.

The relocating section may further comprise a changing section forchanging the target candidate volume selected by the target candidateselecting section. The changing section can cause the target candidatevolume to be selected from among the target candidate volumes having thematching essential attributes but not selected.

For example, the changing section can change the provisionally selectedtarget candidate volumes, in such a manner that the target candidatevolumes do not become concentrated in a particular RAID group, or insuch a manner that data groups having different use statuses, such asdata that is accessed randomly and data that is accessed sequentially,is not located in the same RAID group. The changing section may changethe target candidate volume on the basis of instructions from the user.

The data relocation control device according to another aspect of thepresent invention controls data relocation in a plurality of volumeslocated in a distributed fashion in a plurality of storage devices. Therespective volumes are managed virtually in a unified fashion, by avirtualization section, and a storage section and a control section areprovided. (A) The storage section respectively stores: (a1) volumeattribute information containing, at the least, identificationinformation, the RAID level, drive type, storage capacity, and usestatus, for each of the volumes; and (a2) storage layer managementinformation containing policy identification information forrespectively identifying a plurality of policies that can be defined bya user, and layer composition conditions respectively associated witheach of the policy identification information. (B) The control sectionmay comprise a relocating section for relocating a designated sourcevolume to a designated storage layer, with respect to a plurality ofstorage layers generated respectively on the basis of the storage layermanagement information and the volume attribute information.

A further data relocation control device according to the presentinvention is a device for managing volumes belonging respectively to aplurality of storage devices, in a unified fashion, and controlling therelocation of data stored in each of the volumes; comprising: avirtualization section for managing the volumes belonging to therespective storage devices, virtually, in a unified fashion; a storagesection for storing volume attribute information for managing theattribute information of each of the volumes; and a relocating sectionfor relocating a designated movement source volume to a designatedstorage layer, with respect to a plurality of storage layersrespectively generated on the basis of a plurality of previouslydetermined policies and the volume attribute information.

The present invention may also be interpreted as data relocation methodas described below, for example. More specifically, it is a method forrelocating data stored in a plurality of volumes distributed in aplurality of storage devices, to volumes in the same or differentstorage devices, comprising the steps of: virtually managing all thevolumes belonging to the respective storage devices integrally; managingthe attribute information of respective volumes as volume attributeinformation; previously establishing a plurality of policies; generatinga plurality of storage layers on the basis of this plurality of policiesand the volume attribute information; setting a source volume and atarget storage layer; and relocating a designated source volume to adesignated storage layer among the storage layers.

At least a portion of the means, functions and steps according to thepresent invention may be constituted by computer programs which are readin and executed by a microcomputer. Computer programs of this kind maybe distributed by copying them onto a storage medium, such as a harddisk, optical disk, or the like. Alternatively, computer programs mayalso be supplied via a communications network, such as the Internet.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustrative diagram showing the concept of an embodimentof the present invention;

FIG. 2 is a block diagram showing a general overview of a storagesystem;

FIG. 3 is an illustrative diagram showing a schematic view of a statewhere volumes distributed in an storage system are managed virtually;

FIG. 4 is a block diagram showing the hardware composition of a storagesystem;

FIG. 5 is an illustrative diagram showing the storage structure of thestorage system;

FIG. 6 is a block diagram showing the composition of a storagemanagement server;

FIG. 7 is an illustrative diagram showing the composition of a mappingtable;

FIG. 8 is an illustrative diagram showing the composition of a volumeattribute management table;

FIG. 9 is an illustrative diagram showing the composition of a storagelayer management table;

FIG. 10 is an illustrative diagram showing the composition of acorresponding host management table;

FIG. 11 is an illustrative diagram showing the composition of amigration group management table;

FIG. 12 is an illustrative diagram showing the composition of an actionmanagement table;

FIG. 13 is an illustrative diagram showing a general view of the overalloperation of data relocation;

FIG. 14 is a flowchart showing target candidate selection processing;

FIG. 15 is a flowchart showing relocation implementation processing;

FIG. 16 is an illustrative diagram showing an example of a screen forpresenting a proposal for data relocation;

FIG. 17 is an illustrative diagram showing an example of a screen forrevising the presented plan;

FIG. 18 is a block diagram showing a simplified view of the generalcomposition of a storage system relating to a second embodiment of thepresent invention;

FIG. 19 is an illustrative diagram showing the composition of a volumeattribute management table used in an storage system relating to a thirdembodiment of the present invention;

FIG. 20 is a block diagram showing the general composition of a storagesystem according to a fourth embodiment of the present invention; and

FIG. 21 is an illustrative diagram showing a schematic view of therelationship between a migration group management table and a storagelayer management table.

DESCRIPTION OF THE SPECIFIC EMBODIMENTS

Below, embodiments of the present invention are described with respectto the drawings. FIG. 1 is an illustrative diagram showing a schematicview of the general concepts of the present embodiment. As describedbelow, the storage system according to the present embodiment comprisesa plurality of storage devices A-D.

The volumes belonging to the respective storage devices A-D are managedjointly in a virtual manner, and a host (see FIG. 2) recognizes theplurality of storage devices A-D together, as a single virtual storagedevice.

The respective storage devices A-D respectively comprise volumes A1-A4,B1-B4, C1-C4 and D1-D4. Each of these volumes is a logical storageregion established on a physical storage region provided by a physicalstorage drive, such as a hard disk drive, semiconductor memory drive,optical disk drive, or the like, for example.

Here, the respective storage devices A-D may be provided with drives ofthe same type, or they may respectively combine drives of differenttypes. Therefore, even in the case of volumes located within the samestorage device, there may be differences in the volume attributes, suchas performance, cost, and the like.

The user is able to group the respective volumes belonging to thestorage system, as a plurality of storage layers 1-3. For example, anyone storage layer 1 may be defined as a high-reliability layer. Ahigh-reliability layer is constituted by a group of volumes comprisinghigh-reliability drives, such as fiber channel disks (FC disks), forminga RAID1 array. Furthermore, another storage layer 2 may be defined as alow-cost layer, for example. The low-cost layer is constituted, forexample, by a group of volumes comprising inexpensive drives, such asSATA (Serial AT Attachment) disks, forming a RAID5 array. Furthermore,yet another storage layer 3 may be defined as an archive layer, forexample. The archive layer may be constituted by a group of volumesestablished on inexpensive disks of less than a prescribed capacity, forexample.

As shown in FIG. 1, the respective storage layers 1-3 are constituted ina virtual fashion, spanning the respective storage devices A-D. Morespecifically, the user is able to define a plurality of the volumesconstituting the storage system, as a desired storage layer, such as ahigh-reliability layer, a low-cost layer, a high-speed response layer,an archive layer, or the like, freely, on the basis of the business usestandards (policy). The policy can be set independently of thecomposition of the storage system, and depending on the conditions forconstituting each storage layer, a portion of the volumes may belong toa plurality of storage layers, or alternatively, another portion of thevolumes may not belong to any of the storage layers.

The respective storage layers 1-3 may respectively comprise volumegroups which form objects for data relocation. One example is indicatedby the migration group consisting of two volumes V1, V2 in the storagelayer 1. These volumes V1, V2 are mutually related volumes, for example,volumes storing data groups used by the same application program, ordata groups constituting the same filing system, or the like.

The value of data declines progressively as time passes, for example.Data of high value is located in a high-reliability layer and is usedfrequently by application programs. Desirably, data whose value hasdropped with the passage of time is moved to another storage layer. Thisis because there are limits on the storage resources available in thehigh-reliability layer.

Therefore, the user investigates relocation of the data stored in theplurality of mutually related volumes V1, V2, and decides, for example,to move the data from storage layer 1 to storage layer 3 (which is thearchive layer in this case). The user issues a single instructionindicating relocation of the source volumes V1, V2, and instructs thatthey be moved to storage layer 3.

Thereby, in storage layer 3, which is the movement destination, volumesrespectively capable of storing the volumes V1 and V2 constituting themigration group are selected, and the data is copied to these selectedvolumes. When copying has been completed, the data in the source volumesV1, V2 can be deleted, and these volumes become empty and can be reused.

Here, it is possible previously to associate prescribed actions with therespective storage layers 1-3, in accordance with the policies for therespective storage layers 1-3. An “action” indicates a prescribedinformation process or data operation carried out within the storagelayer. For example, storage layer 1 which is defined as ahigh-reliability layer may be previously associated with a process forgenerating a replica of the relocated data. Moreover, storage layer 2which is defined as a low-cost layer may not be associated previouslywith any action, for example. Furthermore, storage layer 3 which isdefined as an archive layer may be previously associated with aplurality of processes, namely, a process for generating a replica ofthe relocated data, and a process for establishing a read-only accessattribute, for example.

If the volumes V1, V2 constituting the migration group are copied to avolume belonging to storage layer 3, then the prescribed actionassociated with storage layer 3 is carried out automatically. A replicais generated of the data relocated to storage layer 3, and the data isset to a read-only status, thereby prohibiting modification of thatdata.

Here, when the data in the respective volumes V1, V2 is relocated, thenthe volumes to which that data can be copied are selected within thetarget storage layer. Each volume has its own attribute information.Volume attribute information includes, for example, identificationinformation for identifying each volume a RAID level, disk type, storagecapacity, use status indicating whether or not the volume is in use, themodel of storage device to which the volume belongs, and the like.

It is not necessary for all of these volume attributes to be matching inthe source volumes (V1, V2) and the target candidate volumes, and it issufficient for only essential attributes to be matching. An example ofan essential attribute is the storage capacity, for instance. Morespecifically, a volume which has a storage capacity equal to orexceeding the storage capacity of the source volume can be selected as atarget volume.

If more than the required number of volumes having the matchingessential attributes are detected, then the degree of matching of otherattributes apart from the essential attributes is taken intoconsideration, and the volumes having attributes closest to those of thesource volumes can be selected as the target volumes. In this example,the volume attributes are divided broadly into two types: essentialattributes and other attributes, but the composition is not limited tothis and it is also possible, for example, to determine the degree ofmatching between volumes by classifying attributes into three or moretypes, such as essential attributes, semi-essential attributes and otherattributes, for instance, and applying suitable weightings to eachrespective type of attribute.

1. First Embodiment

FIG. 2 is a block diagram showing an approximate view of the generalcomposition of a storage system. As described hereinafter, this storagesystem may be constituted by comprising, for example, a plurality ofhosts 10A and 10B (indicated as “host 10” in the diagram where noparticular distinction is required), a volume virtualization device 20,a plurality of storage devices 30 and 40, a management client 50, and astorage management server 60. These elements are interconnected via acommunications network CN1, such as a LAN (Local Area Network), or thelike.

The hosts 10A and 10B are constituted by a computer system, such as aserver, personal computer, workstation, mainframe computer, portableinformation terminal, or the like. A plurality of open type hosts and aplurality of mainframe type hosts may be combined in the same storagesystem, for example.

The hosts 10A and 10B may be provided with application programs(abbreviated to “App” in the drawings) 11A and 11B (described as“application program 11” where no particular distinction is required),and HBAs (Host Bus Adapters) 12A and 12B (described as “HBA 12” where noparticular distinction is required). A plurality of application programs11 and HBAs 12 may be provided respectively in each one of the hosts 10.

Examples of an application program 11A and 11B include, for example, anelectronic mail management program, a database management program, afile system, or the like. The application programs 11A and 11B may beconnected to a plurality of client terminals located outside the scopeof the drawings, by means of a communications network separate to theplurality of client terminals illustrated, and they may provideinformation processing services in accordance with requests from therespective client terminals.

The HBA 12 is used for transmission and reception of data between thehost and the storage system, and is connected to the volumevirtualization device 20 via a communications network CN2. Here, thecommunications network CN2 is, for example, a LAN, a SAN (Storage AreaNetwork), the Internet, or a dedicated circuit, or the like. In the caseof an open type host, for example, then data transfer is conducted onthe basis of a protocol such as TCP/IP (Transmission ControlProtocol/Internet Protocol), FCP (Fiber Channel Protocol), iSCSI(internet Small Computer System Interface), and the like. If the hostcomputer is a mainframe type host, then data transfer is conducted inaccordance with a communications protocol, such as FICON (FiberConnection: registered trademark), ESCON (Enterprise System Connection:registered trademark), ACONARC (Advanced Connection: Architecture:registered trademark), FIBARC (Fiber Connection Architecture: registeredtrademark), or the like.

Apart from this, the respective hosts 10A and 10B may also berespectively installed with a management program (not illustrated), suchas a path control program, or the like. A management program of thiskind carries out processing for distributing load between a plurality ofHBAs 12 and switching the path when a fault occurs, for example.

The volume virtualization device (hereinafter, also referred to as“virtualization device”) 20 virtualizes the volumes 330, 430, and thelike, present in the storage system, in such a manner that they appearas a single virtual storage device. As shown in FIG. 3(a), for example,the virtualization device 20 presents a plurality of logical volumes(LDEVs) indicated by the identification information LID001-LID 004, tothe respective hosts 10. These logical volumes are respectivelyassociated with other logical volumes indicated by the identificationinformation PID01-PID 04. A logical volume having identificationinformation PID is a physical volume which actually stores data, and alogical volume which can be recognized directly by the host 10 is avirtual volume.

By controlling mapping between the virtual volumes and the physicalvolumes, it is possible to move data in a manner that is transparent tothe host 10. For example, as shown in FIG. 3(b), if data stored in aphysical volume (PID01) is moved to another physical volume (PID02),then after copying the data between these physical volumes, the mappingbetween the physical volume and the virtual volume should bere-established. Alternatively, by exchanging the identificationinformation between the virtual volume (LID001) and the virtual volume(LID002), it is possible to change the device forming the destinationfor data storage, without the host 10 being aware.

In this way, the virtualization device 20 virtualizes the plurality ofphysical volumes of different types located on the storage system, andit manages these volumes in a unified manner and presents the volumes tothe host 10. As described below, the virtualization device 20 may beprovided inside the storage device, or it may be provided in ahigh-performance intelligent switch. Moreover, as described below, thevirtualization device 20 and the storage management server 60 may beprovided in the same computer.

Returning to FIG. 2, the storage devices 30 and 40 respectively compriselogical volumes (physical volumes) 330, 430, and are connectedrespectively to the virtualization device 20, by means of acommunications network CN3, such as a SAN. The storage devices 30 and 40read and write data from and to the volumes, in response to requestsfrom a host 10. An example of the composition of the storage device isdescribed in further detail below.

The management client 50 is, for example, constituted by a computersystem, such as a personal computer, a workstation, or a portableinformation terminal, and it comprises a web browser 51. The user mayissue various types of instructions to the storage system, or acquirevarious types of information from the storage system, for example, bylogging in to the storage management server 60 by means of the webbrowser 51.

The storage management server 60 is a computer system for managingrelocation of volumes in the storage system, and the like. An example ofthe composition of the storage management server 60 is described below,but it may comprise, for example, a data relocation management section632 and a volume database (indicated as “DB” in the drawings) 640.

FIG. 4 is a block diagram showing an approximate view of the hardwarecomposition of the storage system, in a case where the virtualizationdevice 20 is constituted by a storage device.

In this embodiment, the virtualization device 20 may also be called thethird storage device 20. The third storage device 20 can be constitutedby comprising, for example, a plurality of channel adapters(hereinafter, “CHA”) 210, a plurality of disk adapters (hereinafter,“DKA”) 220, a cache memory 230, a shared memory 240, connection controlsections 250 and 260, a storage section 270, and an SVP 280, which arerespectively described hereafter.

The CHAs 210 serve to control transmission and reception of data betweenthe host 10 and the external first storage device 30 and second storagedevice 40, and they may be constituted by a microcomputer systemcomprising a CPU, memory, input/output circuit, and the like, forexample. Each of the CHAs 210 may be provided with a plurality ofcommunications ports 211, and data may be exchanged independently andrespectively via each of these communications ports 211. Each CHA 210corresponds respectively one type of communications protocol, and isprepared in accordance with the type of host 10. However, it is alsopossible for each of the CHAs 210 to be composed so as to correspondrespectively to a plurality of communications protocols.

The DKAs 220 control transmission and reception of data with the storagesection 270. Similarly to the CHAs 210, the DKAs 220 may be constitutedby a microcomputer system comprising a CPU, memory and the like, forexample. For example, each of the DKAs 220 accesses the respective diskdrives 271 and performs data read out or data writing, by converting alogical block address (LBA) designated by the host 10 into an address ona physical disk. The functions of the CHAs 210 and the functions of theDKAs 220 may also be integrated into one or a plurality of controllers.

The cache memory 230 stores write data written from the host 10 and readdata read out from the host 10. The cache memory 230 may be constitutedby a volatile or a non-volatile memory, for example. If the cache memory230 is constituted by a volatile memory, then desirably, a memoryback-up is performed by means of a battery power source, or the like,which is not illustrated. Although not shown in the drawings, the cachememory 230 may be constituted by two regions, namely, a read cacheregion and a write cache region, and the data stored in the write cacheregion may be stored in multi-layered fashion. In other words, sinceread data is also present on the disk drive 271 in exactly the sameform, then even if this read data happens to be lost, it simply needs tobe read out again from the disk drive 271, and hence there is no needfor multi-layered storage. On the other hand, write data is only presentin the cache memory 230 of the storage device 20, and therefore, fromthe viewpoint of reliability it is desirable to store it in amulti-layered fashion. Ultimately, the decision whether or not to storethe cache data in multiple layers depends on the specifications.

The shared memory (which may also be called the control memory) 240 maybe constituted by a non-volatile memory, or it may be constituted by avolatile memory. Control information, management information, and thelike, such as a mapping table T1, for example, is stored in the sharedmemory 240. Information, such as this control information, and the like,can be managed in a multi-layered fashion by means of a plurality ofmemories 240. An example of the composition of this mapping table T1 isdescribed further below.

Here, the shared memory 240 and the cache memory 230 may be constitutedrespectively by separate memory packages, or the cache memory 230 andthe shared memory 240 may be provided in the same memory package.Furthermore, one portion of the memory may be used as a cache region andanother portion thereof may be used as a control region. In other words,the shared memory and the cache memory may also be constituted as thesame memory.

The first connection control section (switch section) 250 respectivelyinterconnects each of the CHAs 210, the DKAs 220, the cache memory 230,and the shared memory 240. Thereby, all of the CHAs 210 and the DKAs 220may respectively access the cache memory 230 and the shared memory 240,in an independent fashion. The connection control section 250 may beconstituted as an ultra-high-speed cross-bar switch, or the like, forexample. The second connection control section 260 respectively connectseach of the DKAs 220 with the storage section 270.

The storage section 270 is constituted by a plurality of disk drives271. The storage section 270 may be provided in the same frame as thecontroller sections, such as the respective CHAs 210 and the respectiveDKAs 220, or it may be provided in a separate frame from the controllersections.

A plurality of disk drives 270 may be provided in the storage section271. For the disk drives 271, it is possible to use an FC disk (fiberchannel disk), a SCSI (Small Computer System Interface) disk, a SATA(Serial AT Attachment) disk, or the like. Moreover, the storage section270 does not have to be constituted by disk drives of the same type, andit is also possible to combine disk drives of a plurality of differenttypes.

Here, in general, the performance declines in order, from an FC disk, toa SCSI disk to a SATA disk. It is possible, for example, to usedifferent types of disk drive according to the state of use of the data,in such a manner that data which is accessed frequently (data of highvalue, or the like) is stored in a high-performance FC disk, and datawhich is accessed infrequently (data of low value, or the like) isstored in a low-performance SATA disk. A plurality of logical storageregions can be provided in a hierarchically layered fashion in thephysical storage regions provided by the respective disk drives 271. Thecomposition of these storage regions is described further below.

The SVP (Service Processor) 280 is connected respectively to each of theCHAs 210 and the DKAs 220, by means of an internal network CN11, such asa LAN. In the diagram the SVP 280 is only connected to the CHAs 210, butthe SVP 280 can also be connected respectively to each of the DKAs 220.The SVP 280 gathers the various statuses within the storage device 20and supplies them to the storage management server 60, either directlyor after processing.

The third storage device 20, which virtualizes the volumes, is an accesspoint for processing data input and output requests from the host 10,and it is connected respectively to the first storage device 30 and thesecond storage device 40, via the communications network CN3. Thedrawing shows a state where two storage devices 30 and 40 are connectedto the storage device 20, but the composition is not limited to this,and one storage device may be connected to the storage device 20, orthree or more storage devices may be connected to the storage device 20.

The first storage device 30 may be constituted by comprising, forexample, a controller 310, a communications port 311 for connecting tothe third storage device 20, and a disk drive 320. The controller 310performs the function of the CHA 210 and DKA 220 described above, andcontrols the transmission and reception of data between the thirdstorage device 20 and the disk drive 320, respectively.

The first storage device 30 may have the same or substantially the samecomposition as the third storage device 20, or it may have a differentcomposition to that of the third storage device 20. The first storagedevice 30 is able to perform data communications with the third storagedevice 20, based on a prescribed communications protocol (for example,FC, iSCSI, or the like), and it should comprise a storage drive (storagedevice), such as a disk drive 320. As described hereinafter, the logicalvolumes belonging to the first storage device 30 are mapped to aprescribed layer of the third storage device 20, and are used exactly asif there where internal volumes of the third storage device 20.

In the present embodiment, an example is illustrated wherein a hard diskis used as a physical storage drive, but the present invention is notlimited to this. Apart from a hard disk, it may also be possible to usea semiconductor memory drive, a magnetic tape drive, an optical diskdrive, a magneto-optical disk drive, or the like, as a storage drive.

Similarly to the first storage device 30, the second storage device 40may be constituted by comprising a controller 410, a disk drive 420, anda port 411, for example. The second storage device 40 may have the samecomposition as the first storage device 30, or it may have a differentcomposition.

FIG. 5 is a compositional diagram focusing on the logical storagestructure of the storage system. Firstly, the composition of the thirdstorage device 20 will be described. The storage structure of the thirdstorage device 20 can be divided broadly into the physical storage layerand the logical storage layer, for example. The physical storage layeris constituted by PDEVs (Physical Devices) 271, which are physicaldisks. The PDEVs correspond to disk drives.

The logical storage layer can be constituted by a plurality of layers(for example, layers of two types). One logical layer may be constitutedby VDEVs (Virtual Devices) 272. The other logical layer may beconstituted by LDEVs (Logical Device) 273.

A VDEV 272 may be constituted by grouping together a prescribed numberof PDEVs 271, in order to form, for instance, one group of four (3D+1P),or one group of eight (7D+1P). One RAID storage region is formed by thecollection of storage regions provided respectively by the PDEVs 271belonging to a group. This RAID storage region forms a VDEV 272.

Here, all of the VDEVs 272 are not actually provided directly on PDEVs271, but rather, some of the VDEVs 272 can be generated in the form of avirtual intermediate device. A virtual VDEV 272 of this kind forms arecipient for mapping the LUs (Logical Units) belonging to the externalstorage devices 30 and 40.

At least one or more LDEVs 273 may be provided on a VDEV 272. LDEVs 273may be formed by dividing up a VDEV 272, into fixed lengths. If the host10 is an open type host, then since the LDEVs 273 are mapped to a LU274, the host 10 recognizes the LDEV 273 as a single physical diskvolume. The open type host 10 accesses a desired LDEV 273 by specifyinga LUN (Logical Unit Number) and a logical block address.

The LU 274 is a device that can be recognized as a logical SCSI unit.Each LU 274 is connected to the host 10 via the port 211A. Each of theLUs 274 can be associated respectively with at least one or more LDEV273. By associating a plurality of LDEVs 273 with one LU 274, it is alsopossible to expand the LU size, in a virtual fashion.

The CMD (Command Device) 275 is a special LU used in order to exchangecommand and status information between a program running on the host 10and the controller of the storage device (CHA 210 and DKA 220). Commandsfrom the host 10 are written to the CMD 275. The controller of thestorage device executes processing corresponding to the command writtento the CMD 275 and writes execution results as status information to theCMD 275. The host 10 reads out and confirms the status written to theCMD 275 and then writes the contents of the processing that is to beexecuted next, to the CMD 275. In this way, the host 10 is able to issuevarious types of instructions to the storage device, via the CMD 275.

The first storage device 30 and the second storage device 40 areconnected respectively via a communications network CN3 to initiatorports (External Port) 211B used for connecting external devices to thethird storage device 20. The first storage device 30 comprises aplurality of PDEVs 320, and an LDEV established on the storage regionprovided by the PDEVs 320. Each LDEV 330 is associated with an LU 340.Similarly, the second storage device 40 is constituted by a plurality ofPDEVs 420 and an LDEV 430, and the LDEV 430 is associated with an LU440.

The LDEV 330 belonging to the first storage device 30 is mapped via theLU 340 to a VDEV 272 of the third storage device 20 (“VDEV2”). The LDEV430 belonging to the second storage device 40 is mapped via the LU 440to a VDEV 272 of the third storage device 20 (“VDEV3”).

By mapping the physical volumes (LDEVs) belonging to the first andsecond storage devices 30 and 40 to a prescribed logical level of thethird storage device 20 in this way, the third storage device 20 is ableto make the volumes 330 and 430, which are located outside it, appear tothe host 10 exactly as if there were volumes belonging to itself. Themethod for incorporating volumes situated outside the third storagedevice 20, into the third storage device 30, is not limited to exampledescribed above.

Next, FIG. 6 is a block diagram showing an approximate view of thehardware composition of the storage management server 60. The storagemanagement server 60 may be constituted, for example, by comprising acommunication section 610, a control section 620, a memory 630, and avolume database 640.

The communication section 610 performs data communications via thecommunications network CN1. The control section 620 performs overallcontrol of the storage management server 60. The memory 630 stores, forexample, a web server program 631, a data relocation management program632, and a database management program 633.

The volume database 640 stores, for example, a volume attributemanagement table T2, a storage layer management table T3, acorresponding host management table T4, a migration group managementtable T5, and an action management table T6. An example of thecomposition of each of these tables is described in further detailbelow.

The web server program 631 provides web server functions in the storagemanagement server 60 by being read in and executed by the controlsection 620. The data relocation management program 632 provides a datarelocation management section in the storage management server 60, bybeing read in by the control section 620. The database management system633 manages the volume database 640. The web server functions, datarelocation management functions, and database management functions maybe executed respectively in a parallel fashion.

FIG. 7 is an illustrative diagram showing the composition of a mappingtable T1. The mapping table T1 is used to map the volumes respectivelybelonging to the first storage device 30 and the second storage device40, to the third storage device 20. The mapping table T1 may also bestored in the shared memory 240 of the third storage device 20.

The mapping table T1 is constituted by associating information, such asthe LUN, LDEV number, maximum slot number (capacity) for LDEV, VDEVnumber, maximum slot number (capacity) for VDEV, device type and pathinformation, for example. The path information can be divided broadlyinto internal path information indicating a path to an internal storageregion of the third storage device 20 (PDEV 271) and external pathinformation indicating a path to a volume belonging to the first storagedevice 30 or the second storage device 40. The external path informationmay include a WWN (World Wide Name) and a LUN, for example.

FIG. 8 shows one example of a volume attribute management table T2. Thevolume attribute management table T2 is used to manage the attributeinformation for the respective volumes distributed in the storagesystem.

The volume attribute management table T2 can be constituted by, forexample, associating each virtual volume with a logical ID foridentifying that virtual volume, a physical ID for the physical volumeassociated with that virtual volume, a RAID level, an emulation type, adisk type, a storage capacity, a use status, and a model of storagedevice.

Here, the RAID level is information that indicates the composition ofthe RAID, such as RAID0, RAID1, RAID5, or the like, for example. Theemulation type is information indicating the structure of the volume;for instance, the emulation type will be different for a volumepresented to an open type host and a volume presented to a mainframetype host. The use status is information indicating whether or not thatvolume is in use. The device model is information indicating the modelof storage device in which that volume is located.

Moreover, the logical ID is a logical volume ID presented to the host 10by the volume virtualization device 20, and the physical ID is an IDindicating the location of the physical volume corresponding to thatlogical volume. The physical ID consists of a device number of thestorage device where the physical volume is stored, and a volume numberwithin that device.

FIG. 9 shows one example of a storage layer management table T3. Thestorage layer management table T3 may be constituted by associating, forexample, a storage layer number, a storage layer name, a conditionformula for defining that storage layer, and an action that is executedautomatically. The action is not an essential setting and it is possibleto define a storage layer without associating an action with it.

The user (system administrator, or the like) may set any desired name asthe storage layer name. For example, he or she may use names, such ashigh-reliability layer, low-cost layer, high-speed response layer,archive layer, or the like, as the storage layer name. The searchconditions for extracting the volumes that are to belong to that storagelayer are set in the condition formula. The search conditions are set bythe user, in accordance with the policy for that storage layer.

Depending on the search conditions, volumes formed by disks of aprescribed type in a prescribed RAID level may be detected (forinstance, “RAID level=RAID1 and disk type=FC”), or volumes located in aparticular storage device may be detected (for instance, “devicemodel=SS1”). For example, in the high-reliability layer (#1), volumesformed by redundant highly reliable FC disks in a RAID1 configurationare selected. Accordingly, it is possible to compose a high-reliabilitylayer by means of highly reliable volumes only. In the low-cost layer(#2), volumes formed by redundant inexpensive SATA disks in a RAID5configuration are selected. Accordingly, it is possible to compose alow-cost layer by means inexpensive volumes of relatively smallcapacity, only. In the high-speed response layer (#3), volumes createdby striping disks (RAID0) located in a device model capable ofhigh-speed response are selected. Accordingly, it is possible to composea high-speed response layer by means of volumes capable of fast I/Oprocessing, without the need for parity calculations, or the like, only.In the archive layer (#4), volumes formed by inexpensive SATA diskshaving less than a prescribed capacity are selected. Accordingly, it ispossible to compose an archive layer by means of low-cost volumes.

As shown in FIG. 9, by searching the volume attribute management tableT2 on the basis of the condition formula set in the storage layermanagement table T3, a group of volumes that should belong to aparticular storage layer are detected. It should be noted here that thestorage layer and the group of volumes are not related directly in anexplicit fashion, but rather, they are related indirectly by means ofthe condition formula. Accordingly, even if the physical composition ofthe storage system has changed in various ways, it is still possible todetermine the correspondence between layers and volumes, easily.

FIG. 10 is an illustrative diagram showing one example of acorresponding host management table T4. The corresponding hostmanagement table T4 may be constituted by associating, for example, alogical ID for identifying a virtual volume, information for identifyingthe host accessing that virtual volume (for example, a domain name), andthe name of the application program using that virtual volume.

FIG. 11 is an illustrative diagram showing one example of a migrationgroup management table T5. A migration group is a unit used whenrelocating data, and in the present embodiment, a migration group isconstituted by a plurality of mutually related volumes, in such a mannerthat data can be relocated with respect to a group unit, in a singleoperation. It is possible to extract a group of mutually relatedvolumes, by searching the corresponding host management table T4illustrated in FIG. 10.

The migration group management table T5 may associate, for example, agroup number, a group name, the logical ID identifying the volumebelonging to that group, and the name of the storage layer to which thatgroup currently belongs. The name of the migration group can bespecified freely by the user. In this way, each migration group may beconstituted by grouping together volumes storing data groups used by thesame application program, or volumes storing data groups forming thesame file system. Furthermore, when data relocation has not yet beenperformed, for instance, immediately after a new migration group hasbeen established, then there may be cases where a storage layer namebelonging to the group has not been set.

FIG. 12 is an illustrative diagram showing one example of an actionmanagement table T6. The action management table T6 defines the specificcontents of the prescribed information processing or data operationpreviously established for a storage layer. The action management tableT6 may be constituted by associating, for example, an ID for identifyingan action, the name of that action, and the script (program) that is tobe executed by that action, for example. Therefore, if an action ID ispreviously set in the storage layer management table T3, then it ispossible to execute a required action by searching the action managementtable T6, using that action ID as a search key.

For example, in the high-reliability layer, an action ID of “A1” is set.The action ID “A1” refers to a mirroring action, and is related withscript for generating a replica of the volume. Consequently, if amigration group is relocated to the high-reliability layer, then areplica of that volume group is generated. Furthermore, in the archivelayer, an action ID of “A3” is set. The action ID “A3” refers to dataarchive processing, and is related with a plurality of scripts requiredfor an archiving process. One of the scripts sets the access attributeto read-only, and the other script creates a replica of the volumegroup. An ID of “A2” in the action management table T6 permits aonce-only write operation, which is known as a WORM (Write Once ReadMany). This action ID is related with script for setting the accessattribute to read-only.

FIG. 13 is an illustrative diagram showing a simplified view of theoverall operation of data relocation. When data relocation is carriedout, the user logs in to the storage management server 60 by means ofthe management client 50, and specifies the migration group to berelocated, and the storage layer forming the destination, respectively(S1).

The storage management server 60 when selects candidate target volumesfor each of the volumes forming the designated migration group (S2). Asdescribed in more detail below, in the process of selecting candidatetarget volumes, one volume to which the data in the source volume can becopied is selected from all of the volumes belonging to the storagelayer specified as the movement destination.

The results of the selection of candidate target volumes by the storagemanagement server 60 are presented to the user, in the form of a volumecorrespondence table T7, for example (S3). The volume correspondencetable T7 may be constituted by associating, for example, a logical ID ofa source volume, and a logical ID of a target volume.

The user confirms the relocation proposal presented by the storagemanagement server 60 (the volume correspondence table T7), by means ofthe web browser 51. If the user approves the proposal from storagemanagement server 60, in its presented form, then relocation is executedat a prescribed timing (S5). If the proposal from the storage managementserver 60 is to be revised, then the user changes the logical ID of thetarget volume by means of the web browser 51 (S4).

FIG. 14 is a flowchart showing processing for selecting target candidatevolumes. This process is initiated, for example, by means of the userexplicitly designating a migration group that is to be relocated, and astorage layer forming the relocation destination (movement destination).

The storage management server 60 (the data relocation management program632) judges whether or not selection of the target candidate volumes hasbeen completed, for all of the source volumes (S11). Here, if thejudgment result is “NO”, then the procedure advances to S12. Byreferring to the volume attribute management table T2, the storagemanagement server 60 extracts volumes which have an “empty” use statusand which match the essential attributes of the source volumes, from thegroup of volumes belonging to the storage layer designated as the targetlayer (S12).

An “essential attribute” is an attribute that is required in order tocopy data between volumes. If any one essential attribute is notmatching, then data cannot be copied between the volumes. In the presentembodiment, examples of essential attributes are the storage capacity,and the emulation type, for instance. In other words, in the presentembodiment, at the very least, the storage capacity and the emulationtype must be matching in the source volume and the target volume.

Next, the storage management server 60 judges the number of volumesdetected to be empty volumes having the matching essential attributes(S13). If there is only one empty volume having the matching essentialattributes, then that volume is selected as the target candidate volume(S14). If no empty volume matching the essential attributes isdiscovered at all, then this means that data cannot be relocated, anderror processing is executed and a report is sent to the user (S16).

If a plurality of empty volumes having the matching essential attributeshave been detected, then the storage management server 60 selects thevolume having the highest degree of matching of the other attributesapart from the essential attributes (non-essential attributes), as themovement candidate volume, (S15). For example, the volume having thehighest number of other attributes which are matching, such as the RAIDlevel, disk type, model of storage device, or the like, is selected as atarget candidate volume. It is also possible to calculate the degree ofmatching by assigning priority rankings to the respective non-essentialattributes. Furthermore, if there are a plurality of volumes having thesame degree of matching in respect of the non-essential attributes, thenthe volume having the smallest logical ID may be selected, for example.

The processing described above is carried out respectively for all ofthe volumes constituting the migration group that is to be moved. Ifcorresponding target candidate volumes have been selected respectivelyfor each one of the source volumes (S11: YES); then the storagemanagement server 60 generates a volume correspondence table T7 andpresents it to the user (S17).

The user checks the volume correspondence table T7 presented by thestorage management server 60 and decides whether to approve it or torevise it. If the user approves the proposal (S18: YES), then thisprocessing sequence terminates. If the user wishes to make changes (S18:NO), then the user can reset the target candidate volumes manually, bymeans of the web browser 51 (S19). When the user has finished revisingthe settings, the processing sequence terminates.

FIG. 15 is a flowchart showing an overview of relocation implementationprocessing. The storage management server 60 (data relocation managementprogram 632) detects the action associated with the storage layerdesignated as the movement destination, by referring to the storagelayer management table T3 (S21).

Thereupon, the storage management server 60 judges whether or notrelocation has been completed for all of the source volumes (S22). Inthe first processing sequence, the judgment result is “NO” and theprocess advances to the next step S23. The data stored in the sourcevolume is copied to the target volume corresponding to that sourcevolume (S23), and the access path is switched from the source volume tothe target volume (S24). By this means, the host 10 is able to accessprescribed data without altering its settings, and without being awareof the fact that the data has been relocated.

The storage management server 60 judges whether or not the movement ofdata from the source volume to the target volume has been completedcorrectly (S25), and if movement of the data has not been completedcorrectly (S25: NO), then error processing is carried out and theprocess terminates.

If the movement of data has been completed correctly (S25: YES), thenthe storage management server 60 checks whether or not there exists anaction that has been associated with the target storage layer (S27). Ifan action has been established for the target storage layer (S27: YES),then the storage management server 60 refers to the action managementtable T6, executes the prescribed script (S28), and then returns to S22.If no action has been established for the target storage layer (S27:NO), then no action is carried out and the sequence returns to S22.

In this way, the data stored respectively in each of the volumesbelonging to the migration group that is to be moved is copiedrespectively to target volumes, and the access paths are changed. Whendata movement has been completed for all of the source volumes (S22:YES), this processing sequence terminates.

FIG. 16 is an illustrative diagram showing a concrete example of thevolume correspondence table T7. The results of the selection of targetcandidate volumes by the storage management server 60 can be displayedby arranging the source volumes and the target volumes in upper andlower rows, as illustrated in FIG. 7, for example. For each of thesource volumes and the target volumes, for example, it is possible todisplay the corresponding logical ID, the RAID group number to which thevolume belongs, the RAID level, the emulation type, and the attributes,such as the storage capacity, and the like.

The user can determine whether or not data relocation is to be executedby checking the screen illustrated in FIG. 16. In order to change thetarget volumes individually, the user operates the modify button B1.When this button B1 is operated, the display changes to the individualrevision screen illustrated in FIG. 17.

In the revision screen illustrated in FIG. 17, the logical ID of thesource volume and the emulation type and storage capacity of the sourcevolume can be displayed in the upper portion of the screen.

The logical ID of the currently selected target volume, and its RAIDgroup, RAID level, physical ID, the number of the storage device towhich it belongs, and the physical ID of the physical volume, and thelike, can be displayed in the central portion of the screen.

In the lower portion of the screen, a list of all of the candidatevolumes which match the essential attributes of the source volume can bedisplayed. The user is able to select any one of the volumes from thevolumes displayed in the volume list in the lower portion of the screen.For example, if the results of the initial selections made by thestorage management server 60 are concentrated in volumes belonging to aparticular RAID group, or if sequentially accessed data and randomlyaccessed data are located in the same RAID group, then the responsecharacteristics of that RAID group will decline. Therefore, the user isable to revise the target volumes, individually, in such a manner thatthe data does not become concentrated in a particular RAID group.

By adopting the composition described above, the present embodiment hasthe following beneficial effects. In the present embodiment, acomposition is adopted wherein a designated source volume is relocatedto a designated storage layer, between a plurality of storage layersrespectively generated on the basis of a plurality of previouslydetermined policies and volume attribute information. Therefore, theuser can define the storage layers freely, in accordance with a desiredpolicy, and can relocate volumes between the storage layers, therebyimproving the usability of the storage system. In particular, in acomplex storage system wherein a plurality of storage devices arecombined, the user is able to relocate data directly in accordance withpolicies set by the user himself or herself, without having to considerthe detailed characteristics of each policy, or the like.

In the present embodiment, it is possible to relocate data in units ofgroups consisting of a plurality of volumes. Therefore, in conjunctionwith a composition wherein data can be relocated between theaforementioned storage layers, it is possible to improve operability forthe user yet further.

In the present embodiment, it is possible previously to associateprescribed actions with a target storage layer, and therefore prescribedactions can be implemented after data relocation has been completed.Therefore, it is possible automatically to implement additional servicesin association with data relocation, and hence situations where the userforgets to carry out certain operations, or the like, can be prevented,and usability can be improved.

In the present embodiment, the matching of essential attributes is takenas a prerequisite condition for target volumes, and the volume havingthe highest degree of matching of attributes other than the essentialattributes is selected as the target candidate volume. Therefore, it ispossible to select appropriate volumes for relocating the data.

2. Second Embodiment

A second embodiment of the present invention is now described on thebasis of FIG. 18. The following embodiments, including the presentembodiment, correspond to modifications of the first embodiment. Thecharacteristic feature of the present embodiment lies in the fact thatthe volume virtualization device 20 and the storage management server 60mentioned in the first embodiment are concentrated in a single volumevirtualization device 70.

The volume virtualization device 70 according to the present embodimentcomprises a volume virtualization section 71, a data relocating section72 and a volume database 73, for example. The volume virtualizationsection 71 realizes similar functions to those of the volumevirtualization device 20 according to the first embodiment. The datarelocating section 72 realizes similar functions to those of the datarelocation management program 632 of the storage management server 60 inthe first embodiment. The volume database 73 stores various tablessimilar to the volume database 64 of the first embodiment.

3. Third Embodiment

A third embodiment of the present invention is now described on thebasis of FIG. 19. The characteristic feature of the present embodimentlies in the fact that dynamic attributes are added to the volumeattribute management table T2 and the storage layers can be defined bytaking these dynamic attributes into consideration.

As shown on the right hand side, the response time for data input andoutput (the I/O response time) can also be managed in the volumeattribute management table T2 of the present embodiment. The I/Oresponse time can be updated by means of the storage management server60 gathering the response time from each of the storage devices 20, 30,40, at regular intervals or irregular intervals, for example. In FIG.19, for the sake of space, the I/O response time is shown instead of thestorage device type, but the model of the storage device can also bemanaged as one of the volume attributes.

In this way, in the present embodiment, since dynamic attributes arealso managed, in addition to static attributes, such as the RAID level,storage capacity, or the like, it is possible to take both staticattributes and dynamic attributes into account when defining the storagelayers. For example, a storage layer where it is sought to achievefaster response time can be constituted from volumes established onhigh-speed disks (FC disks), which are located in a storage device whichhas the smallest value for I/O response time.

4. Fourth Embodiment

A fourth embodiment of the present invention is now described on thebasis of FIG. 20 and FIG. 21. The characteristic feature of the presentembodiment lies in the fact that if there is a change in the compositionof the storage system (if a storage device is removed), then the datastored in a storage device relating to that compositional change isautomatically relocated to a suitable empty volume.

FIG. 20 is an illustrative diagram showing a general overview of astorage system according to the present embodiment. In this storagesystem, a fourth storage device 80 is added to the composition of thefirst embodiment. The fourth storage device 80 can be composed in thesame manner as the storage devices 30 and 40, for example. The fourthstorage device 80 is added here in order to simplify the description,and therefore it is not an essential element in the composition of thepresent invention. The present invention can be implementedsatisfactorily, as long as a plurality of storage devices are provided.

In the present embodiment, an example is described wherein the firststorage device 30 is removed. For example, if the usable life of thefirst storage device 30 has expired, or the like, then the first storagedevice 30 is scheduled for removal. Here, a case where the data groupstored in a storage device 30 scheduled for removal is moved to otherstorage devices 40, 80 (or to the volume virtualization device 20forming a third storage device; same applies hereinafter), will bedescribed on the basis of the illustrative diagram in FIG. 21.

As shown in FIG. 21, firstly, by searching the volume attributemanagement table T2, the user detects a group of volumes having a statusof “in use” which are located on the storage device 30 that is to beremoved, and defines a migration group made up of these volumes. In FIG.21, it is supposed that “device number 1” has been set up in the storagedevice 30 that is to be removed. In the drawings, a migration group namesuch as “withdrawn data volumes” is assigned to the volumes having an“in use” status that are located in the storage device 30 to be removed.

Next, a storage layer is defined based on the condition of “devicenumber is different from device number of storage device to be removed(device number≠1)”. In the diagram, the storage layer name “targetlayer” is assigned to the storage layer constituted by the other storagedevices 40, 80 apart from the storage device 30 that is to be removed.The user then instructs relocation of the aforementioned migration group“withdrawn data volumes”, taking the storage layer assigned with thename “target layer” as the destination.

Thereupon, similarly to the method described in the first embodiment,the data relocation management program 632 respectively selectsappropriate volumes from the storage layer designated as thedestination, namely “target layer”, for each of the volumes contained inthe migration group “withdrawn data volumes” designated as the source,and it presents the selected volumes to the user.

In this way, volumes having a value of “empty” for the volume attribute“use status” and matching the essential attributes, or volumes having avalue of “empty” for the “use status”, matching the essential attributesand having the highest degree of matching in respect of thenon-essential attributes, are selected as suitable target candidatevolumes and presented to the user. If the user approves the assignmentof volumes proposed by the data relocation management program 632, thena relocation process is carried out, and all of the data located in thestorage device 30 that is to be removed is relocated to suitable volumesin the other storage devices 40 and 80.

Moreover, in cases where a new storage device is introduced, or where aportion of existing data is moved to a newly added storage device, inorder to improve performance balance, the storage layer “new layer”should be defined on the basis of the condition “device number=devicenumber of newly added storage device”, and data relocation should becarried out by specifying this storage layer as a destination.Furthermore, as can be seen in the other embodiments also, in thepresent embodiment, it is possible for the user to define storage layershimself or herself, to specify a group of related volumes as a migrationgroup, in one operation, and to carry out data relocation in groupunits.

The present invention is not limited to the embodiments described above.It is possible for a person skilled in the art to make variousadditions, modifications, or the like, without departing from the scopeof the present invention. For example, the migration group does not haveto be constituted by mutually related volumes, and indeed, any volumesmay be grouped together to form a group for movement. Furthermore, thestorage layers may also be established by using the storage devices asunits, namely, a first storage device layer, a second storage devicelayer, a first storage device and second storage device layer, and thelike.

1. A storage system comprising: first and second storage devices, eachof which includes a plurality of physical storages and a controllercoupled to the plurality of physical storages, said first and secondstorage devices having at least one logical volume configured by atleast one of the plurality of physical storages in the respective firstor second storage device; a virtualization device adapted to be coupledto a computer system, and coupled to the first storage device via afirst communication path and to the second storage device via a secondcommunication path, said virtualization device being adapted to manage amap between the logical volumes in the first and second storage devicesand at least one virtual volume constituted by at least one of thelogical volumes so that the virtualization device is able to present thelogical volumes in the first and second storage devices via the at leastone virtual volume to the computer system; and a management device,coupled to the virtualization device, which stores volume attributeinformation of the logical volumes, defines storage layers eachincluding at least two of said logical volumes of said first and secondstorage devices and spanning the first and second storage devices, basedupon the stored volume attribute information of the logical volumes anda policy, relocates a designated source volume from an originatingstorage layer among the defined storage layers to a designated targetstorage layer among the defined storage layers with respect to thepolicy.
 2. The storage system according to claim 1, wherein the policycan be set as desired by a user, and a same logical volume can belong todifferent storage layers.
 3. The storage system according to claim 1,wherein the management device relocates a plurality of designated sourcevolumes, in units of migration groups, each migration group consistingof a plurality of volumes.
 4. The storage system according to claim 3,wherein each migration group is composed of a plurality of volumesstoring mutually related data.
 5. The storage system according to claim1, wherein the management device manages prescribed processing that hasbeen associated previously with the designated target storage layer,with respect to the relocated volume, when the designated source volumehas been relocated to the designated target storage layer.
 6. Thestorage system according to claim 1, wherein, when the management deviceis to relocate the designated source volume to the designated targetstorage layer, the virtualization device invokes a copy operation ofdata of said designated source volume to a target volume belonging tothe designated target storage layer, and upon completion of the copyoperation, changes the access path, from the designated source volume tothe designated target volume.
 7. The storage system according to claim1, wherein the management device selects a target candidate volume towhich the storage contents of the designated source volume can becopied, and presents the target candidate volume selected by themanagement device, to the user; and wherein the management device refersto the volume attribute information and thereby selects a volume havingmatching essential attributes that are previously established from amongthe attributes of the designated source volume, as the target candidatevolume.
 8. The storage system according to claim 7, wherein, if thereare a plurality of target candidate volumes having the matchingessential attributes, then the management device selects one of saidtarget candidate volumes, on the basis of the degree of matching ofother attributes apart from the essential attributes.
 9. The storagesystem according to claim 8, wherein the management device changes thetarget candidate volume selected by the management device, and causesthe target candidate volume to be selected from among the targetcandidate volumes that have the matching essential attributes but arenot selected.
 10. The storage system according to claim 7, wherein theattribute information comprises static attributes and dynamicattributes, and prescribed attributes of the static attributes are setas the essential attributes.
 11. The storage system according to claim7, wherein the essential attributes include, at the least, the storagecapacity of the volume.
 12. The storage system according to claim 1,having storage layer management information containing policyidentification information for identifying each of a plurality ofpolicies, and layer composition conditions respectively associated witheach of the policy identification information; wherein said storagelayers are generated to correspond to the policies respectively by meansof a group of logical volumes satisfying the respective layercomposition conditions.
 13. The storage system according to claim 12,wherein the layer composition conditions include at least one of theRedundant Array of Inexpensive Disks (RAID) level, the drive type, thestorage capacity, the type of storage device, the device number of thestorage device, and the use status. 14-16. (canceled)
 17. A storagesystem comprising: first and second storage devices, each of whichincludes a plurality of physical storages and a controller coupled tothe plurality of physical storages, said first and second storagedevices having at least one logical volume configured by at least one ofthe plurality of physical storages in the respective first or secondstorage device; and a volume virtualization device adapted to be coupledto a computer system, and coupled to the first storage device via afirst communication path and to the second storage device via a secondcommunication path, said volume virtualization device being adapted tomanage a map between the logical volumes in the first and second storagedevices and at least one virtual volume constituted by at least one ofthe logical volumes so that the volume virtualization device is able topresent the logical volumes in the first and second storage devices viathe at least one virtual volume to the computer system, and which storesvolume attribute information of the logical volumes, defines storagelayers each including at least two of said logical volumes of said firstand second storage devices and spanning the first and second storagedevices, based upon the stored volume attribute information of thelogical volumes and a policy, and relocates a designated source volumefrom an originating storage layer among the defined storage layers to adesignated target storage layer among the defined storage layers withrespect to the policy.
 18. The storage system according to claim 17,wherein the policy can be set as desired by a user, and a same logicalvolume can belong to different storage layers.
 19. The storage systemaccording to claim 17, wherein the volume virtualization devicerelocates a plurality of designated source volumes, in units ofmigration groups, each migration group consisting of a plurality ofvolumes.
 20. The storage system according to claim 19, wherein eachmigration group is composed of a plurality of volumes storing mutuallyrelated data.
 21. The storage system according to claim 17, wherein thevolume virtualization device manages prescribed processing that has beenassociated previously with the designated target storage layer, withrespect to the relocated volume, when the designated source volume hasbeen relocated to the designated target storage layer.
 22. The storagesystem according to claim 17, wherein, when the volume virtualizationdevice is to relocate the designated source volume to the designatedtarget storage layer, the volume virtualization device invokes a copyoperation of data of said designated source volume to a target volumebelonging to the designated target storage layer, and upon completion ofthe copy operation, changes the access path, from the designated sourcevolume to the designated target volume.
 23. The storage system accordingto claim 17, wherein the volume virtualization device selects a targetcandidate volume to which the storage contents of the designated sourcevolume can be copied, and presents the target candidate volume selectedby the volume virtualization device, to the user; and wherein the volumevirtualization device refers to the volume attribute information andthereby selects a volume having matching essential attributes that arepreviously established from among the attributes of the designatedsource volume, as the target candidate volume.
 24. The storage systemaccording to claim 23, wherein, if there are a plurality of targetcandidate volumes having the matching essential attributes, then thevolume virtualization device selects one of said target candidatevolumes, on the basis of the degree of matching of other attributesapart from the essential attributes.
 25. The storage system according toclaim 24, wherein the volume virtualization device changes the targetcandidate volume selected by the volume virtualization device, andcauses the target candidate volume to be selected from among the targetcandidate volumes that have the matching essential attributes but arenot selected.
 26. The storage system according to claim 23, wherein theattribute information comprises static attributes and dynamicattributes, and prescribed attributes of the static attributes are setas the essential attributes.
 27. The storage system according to claim23, wherein the essential attributes include, at the least, the storagecapacity of the volume.
 28. The storage system according to claim 17,having storage layer management information containing policyidentification information for identifying each of a plurality ofpolicies, and layer composition conditions respectively associated witheach of the policy identification information; wherein said storagelayers are generated to correspond to the policies respectively by meansof a group of logical volumes satisfying the respective layercomposition conditions.
 29. The storage system according to claim 28,wherein the layer composition conditions include at least one of theRedundant Array of Inexpensive Disks (RAID) level, the drive type, thestorage capacity, the type of storage device, the device number of thestorage device, and the use status.
 30. A storage system comprising:first and second storage devices, each of which includes a plurality ofphysical storages and a controller coupled to the plurality of physicalstorages, said first and second storage devices having at least onelogical volume configured by at least one of the plurality of physicalstorages in the respective first or second storage device; and a thirdstorage device adapted to manage a map between the logical volumes inthe first and second storage devices and at least one virtual volumeconstituted by at least one of the logical volumes so that the thirdstorage device is able to present the logical volumes in the first andsecond storage devices via the at least one virtual volume to a computersystem, and which stores volume attribute information of the logicalvolumes, defines storage layers each including at least two of saidlogical volumes of said first and second storage devices and spanningthe first and second storage devices, based upon the stored volumeattribute information of the logical volumes and a policy, and relocatesa designated source volume from an originating storage layer among thedefined storage layers to a designated target storage layer among thedefined storage layers with respect to the policy.
 31. The storagesystem according to claim 30, wherein the policy can be set as desiredby a user, and a same logical volume can belong to different storagelayers.
 32. The storage system according to claim 30, wherein the thirdstorage device relocates a plurality of designated source volumes, inunits of migration groups, each migration group consisting of aplurality of volumes.
 33. The storage system according to claim 32,wherein each migration group is composed of a plurality of volumesstoring mutually related data.
 34. The storage system according to claim30, wherein the third storage device manages prescribed processing thathas been associated previously with the designated target storage layer,with respect to the relocated volume, when the designated source volumehas been relocated to the designated target storage layer.
 35. Thestorage system according to claim 30, wherein, when the third storagedevice is to relocate the designated source volume to the designatedtarget storage layer, the third storage device invokes a copy operationof data of said designated source volume to a target volume belonging tothe designated target storage layer, and upon completion of the copyoperation, changes the access path, from the designated source volume tothe designated target volume.
 36. The storage system according to claim30, wherein the third storage device selects a target candidate volumeto which the storage contents of the designated source volume can becopied, and presents the target candidate volume selected by the thirdstorage device, to the user; and wherein the third storage device refersto the volume attribute information and thereby selects a volume havingmatching essential attributes that are previously established from amongthe attributes of the designated source volume, as the target candidatevolume.
 37. The storage system according to claim 36, wherein, if thereare a plurality of target candidate volumes having the matchingessential attributes, then the third storage device selects one of saidtarget candidate volumes, on the basis of the degree of matching ofother attributes apart from the essential attributes.
 38. The storagesystem according to claim 37, wherein the third storage device changesthe target candidate volume selected by the third storage device, andcauses the target candidate volume to be selected from among the targetcandidate volumes that have the matching essential attributes but arenot selected.
 39. The storage system according to claim 36, wherein theattribute information comprises static attributes and dynamicattributes, and prescribed attributes of the static attributes are setas the essential attributes.
 40. The storage system according to claim36, wherein the essential attributes include, at the least, the storagecapacity of the volume.
 41. The storage system according to claim 30,having storage layer management information containing policyidentification information for identifying each of a plurality ofpolicies, and layer composition conditions respectively associated witheach of the policy identification information; wherein said storagelayers are generated to correspond to the policies respectively by meansof a group of logical volumes satisfying the respective layercomposition conditions.
 42. The storage system according to claim 41,wherein the layer composition conditions include at least one of theRedundant Array of Inexpensive Disks (RAID) level, the drive type, thestorage capacity, the type of storage device, the device number of thestorage device, and the use status.